AN INTEGRATION OF GEOPHYSICAL METHODS FOR THE DETERMINATION OF SUBSURFACE STRUCTURE OF INTRA-MOUNTAIN BASINS: THE CASE OF LEONESSA PLAIN (CENTRAL APENNINES, ITALY)

About the thesis. This thesis describes the results of a research approach that integrated a detailed gravity survey with singlestation microtremor observations to evaluate the thickness of the alluviallacustrine sedimentary infilling, the bedrock structure of the Leonessa basin, and to reconstruct of the main steps of the basin evolution. The Leonessa basin, the test-area of this study, is located in the heart of the Central Apennines, in the northern Latium region. The city of Leonessa is located at 980 m a. s. l., about 36 km NNE of the town of Rieti, on the southern part of the homonymous basin. The Leonessa Plain is one of the major intra-mountain basins of Center Apennines, related to the Plio-Quaternary extensional tectonic. The area is characterized by a very high value of seismic hazard with respect to the rest of the Latium region, with a range of acceleration value between 0.25 – 0.278g (10% probability of exceedance in 50 years) on flat bedrock. According to the DGR n. 387 of May 22, 2009 “New Seismic Classification of the Territory of Latium Region”, the Leonessa city is classified as Seismic Area 1. During this research activity, it is intended to highlight the indispensable significance of the geophysical methods at the level of primary decision-making at urban planning studies and to help resolving a range of problems connected to risk assessment. To this purpose, 333 gravity stations and 29 single station microtremor observations were made to covered an area of 63 km2. Because of the complexity and active tectonic of the study area, an irregular valley shape was expected.